Update, Tuesday, 12:30 p.m.
The Frazier Fire, which started burning near Nacimiento Lake on Monday afternoon, had scorched 86 acres as of Tuesday afternoon.
Containment remains at 50 percent, according to a Cal Fire news release. Firefighters worked through the night to prevent the blaze, which burned grass and oak woodlands.
Full containment is expected Wednesday afternoon.
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Nacimiento Lake Drive is open in both directions. Motorists are advised to use caution, as crews will continue mopping up the fire throughout the next few days.
The cause of the fire remains under investigation.
Update, 7:20 p.m. Monday
The fire burning near Nacimiento Lake on Monday evening was 50 percent contained as of 7 p.m., according to Cal Fire officials.
A fire near Nacimiento Lake that started about 2 p.m. Monday burned 75 acres and was about 20 percent contained as of 5 p.m., according to Cal Fire officials.
The blaze, called the Frazier Fire, broke out near Nacimiento Lake Drive and Frazier Road.
No homes or other structures have been threatened, and no evacuations have taken place, fire Capt. David Kay said.
The fire threatened power lines, and some people in the area were without electricity. Officials from PG&E were sent out to monitor the power lines.
Nacimiento Lake Drive was closed from the lake to Chimney Rock Road.
The cause of the fire is under investigation.